noun

• (figurative) That which conceals; a disguise or pretext.
  "For neither at any time vſed wee flattering wordes, as yee knowe, nor a cloke of couetouſneſſe, God is witneſſe: […]"
• (Internet) A text replacement for an IRC user's hostname or IP address, making the user less identifiable.

verb

• (transitive) To cover as with or like a cloak.
  "He would hold her, just hold her, while his hands soothed the bare skin of her arms and the delicate fabric that cloaked her shoulders and her back."
• (transitive, figurative) To cover up, hide or conceal.
  "It’s possible that some microbes don’t just take up residence in tumors but help them grow. They may cloak the tumor from the immune system, neutralize drugs or help tumors spread through the body."
• (science fiction, ambitransitive) To render or become invisible via futuristic technology.
  "The ship cloaked before entering the enemy sector of space."